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The luminescent spectra of the RE2O3-doped P2O5–CdO–ZnO glasses (RE = Er, and Tb) were investigated to separate the effects of two studied rare-earth elements and the annealing regime on the emission performance of the prepared glasses. The glasses undergo a series of collective measurements including UV–visible absorption, luminescence, thermal expansion, XRD, TEM, and FTIR. The optical UV–visible spectra of the two doped glasses reveal a UV band due to undoped glass beside and extra extended 11 peaks with the Er3+ ions with high distinct features while the Tb3+ ions samples exhibit peaks within the visible region. These peaks are correlated with transitions from the ground state in each case to specific energy transitions. The overall optical data indicate that the two rare earth ions are present in a stable trivalent state. Under UV excitation, both Er3+ and Tb3+ emit a characteristic green light corresponding to 4S3/2 → 4I15/2 and 5D4 → 7F5 transitions, respectively. The performance of the green light was identified to be enhanced by increasing the concentration of rare earth and the effect of annealing temperature. Moreover, the intensity of the infrared emission of Er3+ at 1532 nm corresponds to the (4I13/2 → 4I15/2) transition which is assumed to be developed with the effect of heating. The resultant IR spectra show distinct vibrational peaks due to phosphate groups that undergo only minor modifications when doped with rare earth elements or over-annealed. [ABSTRACT FROM AUTHOR]

Multicomponent fluorophosphate host glass and samples containing Pr2O3 as dopant oxide with added (0.25, 0.5, 1.0 or 2 wt%) were prepared by melting and annealing technique. Multiple characterization techniques were employed to investigate optical, photoluminescence and FTIR spectral properties of the prepared glasses before and after being gamma irradiated with doses of 2, 9 Mrad. Optical absorption spectra reveal only distinct UV absorption in the undoped glass which is related to trace iron impurities while the Pr2O3-doped samples exhibit two series of characteristic extended peaks within the visible and near-IR regions which are due to absorption of Pr3+ ions. Gamma irradiation causes a continuous increase of the intensity of the UV absorption with irradiation. The Pr2O3-doped samples reveal obvious effects including the shift of the absorption to longer wavelength only of the first visible series of absorption peaks while the second series of peaks in the near IR region remain almost unchanged. These optical changes upon irradiation are suggested to be related to photochemical reactions with the liberated pairs of electrons and positive holes during the irradiation process. Photoluminescence (PL) measurements indicate the appearance of five emission peaks and three excited peaks before irradiation and their intensities increase with the Pr2O3 content. With irradiation, the PL spectra reveal limited changes with 2 Mrad but with 9 Mrad, the first emission peaks show few variations but the main high intense peak at 600 nm remains unchanged but the intensities of the peaks become very close with the increase of Pr2O3 content. The PL results support the stability of the Pr3+ ions as evidenced by the persistence of the optical absorption spectra. FTIR spectra of the studied glasses reveal the appearance of repetitive vibrational bands due to main building PO4 units mainly with Q2 and Q3 units with some suggested fluorophosphates groups (PO3F)− AlF4 (AlFO) groups. Gamma irradiation decreases the intensities of some bands together with the generation of a distinct band at 1455 cm−1. The FTIR results indicate the maintenance of the vibratonal bands after irradiation and the changes in the intensity of some bands are related to suggested variations in the bond angles and/or bond lengths of structural phosphate groups. [ABSTRACT FROM AUTHOR]

Glass matrices of nominal composition 90% PbO-10% SiO2 with progressive partial replacement of PbO by B2O3 have been prepared using the conventional melting and annealing method. Collective Fourier transform infrared (FTIR) and optical absorption spectral measurements recorded before and after irradiation with a final gamma ray dose (8 Mrad) were employed to manifest the role of B2O3 on the studied properties of high lead silicate glasses. Optical spectra reveal extended UV/vis. absorption spectral bands resulting from absorption from both lead ions and trace iron impurities. FTIR absorption spectral measurements indicate the appearance of compact mid IR spectra correlated with the presence of multifunctional mixed vibrating groups including SiO4, BO3, BO4 and PbO4. The application of the deconvolution analysis technique (DAT) enables the identification of mixed or hidden peaks associated with different vibrational modes due to the expected structural groups from silicate and Pb-O linkages. Gamma irradiation of glasses produces stable and slightly affected spectral bands which can be assigned to the presence of lead oxide in high percent which causes shielding and retarding characteristics towards gamma irradiation to reduce passage of generated positive holes and electrons throughout the irradiation process. [ABSTRACT FROM AUTHOR]

Multicomponent lithium borate glasses containing either CaF2 or MgF2 and doped with 0.125 → 0.5% Ho2O3 replacing Li2O were prepared by the melting and annealing technique. The optical, FTIR, photoluminescence spectral and thermal properties of the prepared glasses were examined. The glasses were subjected to the controlled heat treatment two-step regime to be converted to their corresponding glass-ceramics. X-ray diffraction studies indicate the separation of different crystalline phases upon heat treatment in accordance with the presence of either CaF2 or MgF2. The optical spectral measurements of the two undoped glasses show a prominent UV absorption which is due to unavoidable contaminated trace iron impurities, while Ho2O3-doped glasses show additional extended visible-near IR absorption peaks which are related to absorption of Ho3+ ions. Structural FTIR measurements indicate the appearance of nearly similar condensed vibrational bands within the range 400-1600 cm−1 which are correlated with the presence of both triangular and tetrahedral borate groups within their distinct varying wavenumbers. The IR spectra of the glass-ceramic derivatives resemble to a large extent that for their parent glasses with minor variations. The photoluminescence (PL) spectra reveal four distinct excitation peaks within the range 365 → 453 nm and two emission peaks at about 480 and 575 nm. The glass-ceramics PL spectra show minor variations. The thermal expansion curves of the selected undoped and high 0.5 Ho2O3-doped glass from the two studied series show comparable thermal parameters revealing some variations within the thermal data in accordance with the suggested different housing behaviors of constitutional MgF2 or CaF2. The calculated optical parameters data involving the optical bandgap, Urbach energy, and refractive index are assumed to be correlated with the constitutional network structure of glass and its change with variations in the glass composition or percent of dopant oxide. [ABSTRACT FROM AUTHOR]

Multicomponent lithium borate glasses containing either CaF2 or MgF2 and doped with 0.125 → 0.5% Ho2O3 replacing Li2O were prepared by the melting and annealing technique. The optical, FTIR, photoluminescence spectral and thermal properties of the prepared glasses were examined. The glasses were subjected to the controlled heat treatment two-step regime to be converted to their corresponding glass-ceramics. X-ray diffraction studies indicate the separation of different crystalline phases upon heat treatment in accordance with the presence of either CaF2 or MgF2. The optical spectral measurements of the two undoped glasses show a prominent UV absorption which is due to unavoidable contaminated trace iron impurities, while Ho2O3-doped glasses show additional extended visible-near IR absorption peaks which are related to absorption of Ho3+ ions. Structural FTIR measurements indicate the appearance of nearly similar condensed vibrational bands within the range 400-1600 cm−1 which are correlated with the presence of both triangular and tetrahedral borate groups within their distinct varying wavenumbers. The IR spectra of the glass-ceramic derivatives resemble to a large extent that for their parent glasses with minor variations. The photoluminescence (PL) spectra reveal four distinct excitation peaks within the range 365 → 453 nm and two emission peaks at about 480 and 575 nm. The glass-ceramics PL spectra show minor variations. The thermal expansion curves of the selected undoped and high 0.5 Ho2O3-doped glass from the two studied series show comparable thermal parameters revealing some variations within the thermal data in accordance with the suggested different housing behaviors of constitutional MgF2 or CaF2. The calculated optical parameters data involving the optical bandgap, Urbach energy, and refractive index are assumed to be correlated with the constitutional network structure of glass and its change with variations in the glass composition or percent of dopant oxide. [ABSTRACT FROM AUTHOR]